blob: 81ab0dfd67679505cee3f9e1fa37a2be5cb30338 [file] [log] [blame]
bigbiff bigbiffe60683a2013-02-22 20:55:50 -05001/*
2 * read.c - read the blkid cache from disk, to avoid scanning all devices
3 *
4 * Copyright (C) 2001, 2003 Theodore Y. Ts'o
5 * Copyright (C) 2001 Andreas Dilger
6 *
7 * %Begin-Header%
8 * This file may be redistributed under the terms of the
9 * GNU Lesser General Public License.
10 * %End-Header%
11 */
12
13
14#include <stdio.h>
15#include <ctype.h>
16#include <string.h>
17#include <time.h>
18#include <sys/types.h>
19#include <sys/stat.h>
20#include <fcntl.h>
21#include <unistd.h>
22#ifdef HAVE_ERRNO_H
23#include <errno.h>
24#endif
25
26#include "blkidP.h"
27
28#ifdef HAVE_STDLIB_H
29# ifndef _XOPEN_SOURCE
30# define _XOPEN_SOURCE 600 /* for inclusion of strtoull */
31# endif
32# include <stdlib.h>
33#endif
34
35#ifdef HAVE_STRTOULL
36#define STRTOULL strtoull /* defined in stdlib.h if you try hard enough */
37#else
38/* FIXME: need to support real strtoull here */
39#define STRTOULL strtoul
40#endif
41
42#ifdef TEST_PROGRAM
43#define blkid_debug_dump_dev(dev) (debug_dump_dev(dev))
44static void debug_dump_dev(blkid_dev dev);
45#endif
46
47/*
48 * File format:
49 *
50 * <device [<NAME="value"> ...]>device_name</device>
51 *
52 * The following tags are required for each entry:
53 * <ID="id"> unique (within this file) ID number of this device
54 * <TIME="sec.usec"> (time_t and suseconds_t) time this entry was last
55 * read from disk
56 * <TYPE="type"> (detected) type of filesystem/data for this partition
57 *
58 * The following tags may be present, depending on the device contents
59 * <LABEL="label"> (user supplied) label (volume name, etc)
60 * <UUID="uuid"> (generated) universally unique identifier (serial no)
61 */
62
63static char *skip_over_blank(char *cp)
64{
65 while (*cp && isspace(*cp))
66 cp++;
67 return cp;
68}
69
70static char *skip_over_word(char *cp)
71{
72 char ch;
73
74 while ((ch = *cp)) {
75 /* If we see a backslash, skip the next character */
76 if (ch == '\\') {
77 cp++;
78 if (*cp == '\0')
79 break;
80 cp++;
81 continue;
82 }
83 if (isspace(ch) || ch == '<' || ch == '>')
84 break;
85 cp++;
86 }
87 return cp;
88}
89
90static char *strip_line(char *line)
91{
92 char *p;
93
94 line = skip_over_blank(line);
95
96 p = line + strlen(line) - 1;
97
98 while (*line) {
99 if (isspace(*p))
100 *p-- = '\0';
101 else
102 break;
103 }
104
105 return line;
106}
107
108#if 0
109static char *parse_word(char **buf)
110{
111 char *word, *next;
112
113 word = *buf;
114 if (*word == '\0')
115 return NULL;
116
117 word = skip_over_blank(word);
118 next = skip_over_word(word);
119 if (*next) {
120 char *end = next - 1;
121 if (*end == '"' || *end == '\'')
122 *end = '\0';
123 *next++ = '\0';
124 }
125 *buf = next;
126
127 if (*word == '"' || *word == '\'')
128 word++;
129 return word;
130}
131#endif
132
133/*
134 * Start parsing a new line from the cache.
135 *
136 * line starts with "<device" return 1 -> continue parsing line
137 * line starts with "<foo", empty, or # return 0 -> skip line
138 * line starts with other, return -BLKID_ERR_CACHE -> error
139 */
140static int parse_start(char **cp)
141{
142 char *p;
143
144 p = strip_line(*cp);
145
146 /* Skip comment or blank lines. We can't just NUL the first '#' char,
147 * in case it is inside quotes, or escaped.
148 */
149 if (*p == '\0' || *p == '#')
150 return 0;
151
152 if (!strncmp(p, "<device", 7)) {
bigbiff7b4c7a62015-01-01 19:44:14 -0500153 DBG(READ, ul_debug("found device header: %8s", p));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500154 p += 7;
155
156 *cp = p;
157 return 1;
158 }
159
160 if (*p == '<')
161 return 0;
162
163 return -BLKID_ERR_CACHE;
164}
165
166/* Consume the remaining XML on the line (cosmetic only) */
167static int parse_end(char **cp)
168{
169 *cp = skip_over_blank(*cp);
170
171 if (!strncmp(*cp, "</device>", 9)) {
bigbiff7b4c7a62015-01-01 19:44:14 -0500172 DBG(READ, ul_debug("found device trailer %9s", *cp));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500173 *cp += 9;
174 return 0;
175 }
176
177 return -BLKID_ERR_CACHE;
178}
179
180/*
181 * Allocate a new device struct with device name filled in. Will handle
182 * finding the device on lines of the form:
183 * <device foo=bar>devname</device>
184 * <device>devname<foo>bar</foo></device>
185 */
186static int parse_dev(blkid_cache cache, blkid_dev *dev, char **cp)
187{
188 char *start, *tmp, *end, *name;
189 int ret;
190
191 if ((ret = parse_start(cp)) <= 0)
192 return ret;
193
194 start = tmp = strchr(*cp, '>');
195 if (!start) {
bigbiff7b4c7a62015-01-01 19:44:14 -0500196 DBG(READ, ul_debug("blkid: short line parsing dev: %s", *cp));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500197 return -BLKID_ERR_CACHE;
198 }
199 start = skip_over_blank(start + 1);
200 end = skip_over_word(start);
201
bigbiff7b4c7a62015-01-01 19:44:14 -0500202 DBG(READ, ul_debug("device should be %*s",
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500203 (int)(end - start), start));
204
205 if (**cp == '>')
206 *cp = end;
207 else
208 (*cp)++;
209
210 *tmp = '\0';
211
212 if (!(tmp = strrchr(end, '<')) || parse_end(&tmp) < 0) {
bigbiff7b4c7a62015-01-01 19:44:14 -0500213 DBG(READ, ul_debug("blkid: missing </device> ending: %s", end));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500214 } else if (tmp)
215 *tmp = '\0';
216
217 if (end - start <= 1) {
bigbiff7b4c7a62015-01-01 19:44:14 -0500218 DBG(READ, ul_debug("blkid: empty device name: %s", *cp));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500219 return -BLKID_ERR_CACHE;
220 }
221
222 name = strndup(start, end - start);
223 if (name == NULL)
224 return -BLKID_ERR_MEM;
225
bigbiff7b4c7a62015-01-01 19:44:14 -0500226 DBG(READ, ul_debug("found dev %s", name));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500227
228 if (!(*dev = blkid_get_dev(cache, name, BLKID_DEV_CREATE))) {
229 free(name);
230 return -BLKID_ERR_MEM;
231 }
232
233 free(name);
234 return 1;
235}
236
237/*
238 * Extract a tag of the form NAME="value" from the line.
239 */
240static int parse_token(char **name, char **value, char **cp)
241{
242 char *end;
243
244 if (!name || !value || !cp)
245 return -BLKID_ERR_PARAM;
246
247 if (!(*value = strchr(*cp, '=')))
248 return 0;
249
250 **value = '\0';
251 *name = strip_line(*cp);
252 *value = skip_over_blank(*value + 1);
253
254 if (**value == '"') {
bigbiff7b4c7a62015-01-01 19:44:14 -0500255 char *p = end = *value + 1;
256
257 /* convert 'foo\"bar' to 'foo"bar' */
258 while (*p) {
259 if (*p == '\\') {
260 p++;
261 *end = *p;
262 } else {
263 *end = *p;
264 if (*p == '"')
265 break;
266 }
267 p++;
268 end++;
269 }
270
271 if (*end != '"') {
272 DBG(READ, ul_debug("unbalanced quotes at: %s", *value));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500273 *cp = *value;
274 return -BLKID_ERR_CACHE;
275 }
276 (*value)++;
277 *end = '\0';
bigbiff7b4c7a62015-01-01 19:44:14 -0500278 end = ++p;
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500279 } else {
280 end = skip_over_word(*value);
281 if (*end) {
282 *end = '\0';
283 end++;
284 }
285 }
286 *cp = end;
287
288 return 1;
289}
290
291/*
292 * Extract a tag of the form <NAME>value</NAME> from the line.
293 */
294/*
295static int parse_xml(char **name, char **value, char **cp)
296{
297 char *end;
298
299 if (!name || !value || !cp)
300 return -BLKID_ERR_PARAM;
301
302 *name = strip_line(*cp);
303
304 if ((*name)[0] != '<' || (*name)[1] == '/')
305 return 0;
306
307 FIXME: finish this.
308}
309*/
310
311/*
312 * Extract a tag from the line.
313 *
314 * Return 1 if a valid tag was found.
315 * Return 0 if no tag found.
316 * Return -ve error code.
317 */
318static int parse_tag(blkid_cache cache, blkid_dev dev, char **cp)
319{
320 char *name = NULL;
321 char *value = NULL;
322 int ret;
323
324 if (!cache || !dev)
325 return -BLKID_ERR_PARAM;
326
327 if ((ret = parse_token(&name, &value, cp)) <= 0 /* &&
328 (ret = parse_xml(&name, &value, cp)) <= 0 */)
329 return ret;
330
331 /* Some tags are stored directly in the device struct */
332 if (!strcmp(name, "DEVNO"))
333 dev->bid_devno = STRTOULL(value, 0, 0);
334 else if (!strcmp(name, "PRI"))
335 dev->bid_pri = strtol(value, 0, 0);
336 else if (!strcmp(name, "TIME")) {
337 char *end = NULL;
338 dev->bid_time = STRTOULL(value, &end, 0);
339 if (end && *end == '.')
340 dev->bid_utime = STRTOULL(end + 1, 0, 0);
341 } else
342 ret = blkid_set_tag(dev, name, value, strlen(value));
343
bigbiff7b4c7a62015-01-01 19:44:14 -0500344 DBG(READ, ul_debug(" tag: %s=\"%s\"", name, value));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500345
346 return ret < 0 ? ret : 1;
347}
348
349/*
350 * Parse a single line of data, and return a newly allocated dev struct.
351 * Add the new device to the cache struct, if one was read.
352 *
353 * Lines are of the form <device [TAG="value" ...]>/dev/foo</device>
354 *
355 * Returns -ve value on error.
356 * Returns 0 otherwise.
357 * If a valid device was read, *dev_p is non-NULL, otherwise it is NULL
358 * (e.g. comment lines, unknown XML content, etc).
359 */
360static int blkid_parse_line(blkid_cache cache, blkid_dev *dev_p, char *cp)
361{
362 blkid_dev dev;
363 int ret;
364
365 if (!cache || !dev_p)
366 return -BLKID_ERR_PARAM;
367
368 *dev_p = NULL;
369
bigbiff7b4c7a62015-01-01 19:44:14 -0500370 DBG(READ, ul_debug("line: %s", cp));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500371
372 if ((ret = parse_dev(cache, dev_p, &cp)) <= 0)
373 return ret;
374
375 dev = *dev_p;
376
377 while ((ret = parse_tag(cache, dev, &cp)) > 0) {
378 ;
379 }
380
381 if (dev->bid_type == NULL) {
bigbiff7b4c7a62015-01-01 19:44:14 -0500382 DBG(READ, ul_debug("blkid: device %s has no TYPE",dev->bid_name));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500383 blkid_free_dev(dev);
384 goto done;
385 }
386
bigbiff7b4c7a62015-01-01 19:44:14 -0500387 DBG(READ, blkid_debug_dump_dev(dev));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500388
389done:
390 return ret;
391}
392
393/*
394 * Parse the specified filename, and return the data in the supplied or
395 * a newly allocated cache struct. If the file doesn't exist, return a
396 * new empty cache struct.
397 */
398void blkid_read_cache(blkid_cache cache)
399{
400 FILE *file;
401 char buf[4096];
402 int fd, lineno = 0;
403 struct stat st;
404
405 if (!cache)
406 return;
407
408 /*
409 * If the file doesn't exist, then we just return an empty
410 * struct so that the cache can be populated.
411 */
412 if ((fd = open(cache->bic_filename, O_RDONLY|O_CLOEXEC)) < 0)
413 return;
414 if (fstat(fd, &st) < 0)
415 goto errout;
416 if ((st.st_mtime == cache->bic_ftime) ||
417 (cache->bic_flags & BLKID_BIC_FL_CHANGED)) {
bigbiff7b4c7a62015-01-01 19:44:14 -0500418 DBG(CACHE, ul_debug("skipping re-read of %s",
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500419 cache->bic_filename));
420 goto errout;
421 }
422
bigbiff7b4c7a62015-01-01 19:44:14 -0500423 DBG(CACHE, ul_debug("reading cache file %s",
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500424 cache->bic_filename));
425
bigbiff7b4c7a62015-01-01 19:44:14 -0500426 file = fdopen(fd, "r" UL_CLOEXECSTR);
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500427 if (!file)
428 goto errout;
429
430 while (fgets(buf, sizeof(buf), file)) {
431 blkid_dev dev;
432 unsigned int end;
433
434 lineno++;
435 if (buf[0] == 0)
436 continue;
437 end = strlen(buf) - 1;
438 /* Continue reading next line if it ends with a backslash */
439 while (end < (sizeof(buf) - 2) && buf[end] == '\\' &&
440 fgets(buf + end, sizeof(buf) - end, file)) {
441 end = strlen(buf) - 1;
442 lineno++;
443 }
444
445 if (blkid_parse_line(cache, &dev, buf) < 0) {
bigbiff7b4c7a62015-01-01 19:44:14 -0500446 DBG(READ, ul_debug("blkid: bad format on line %d", lineno));
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500447 continue;
448 }
449 }
450 fclose(file);
451
452 /*
453 * Initially we do not need to write out the cache file.
454 */
455 cache->bic_flags &= ~BLKID_BIC_FL_CHANGED;
456 cache->bic_ftime = st.st_mtime;
457
458 return;
459errout:
460 close(fd);
461 return;
462}
463
464#ifdef TEST_PROGRAM
465static void debug_dump_dev(blkid_dev dev)
466{
467 struct list_head *p;
468
469 if (!dev) {
470 printf(" dev: NULL\n");
471 return;
472 }
473
474 printf(" dev: name = %s\n", dev->bid_name);
475 printf(" dev: DEVNO=\"0x%0llx\"\n", (long long)dev->bid_devno);
476 printf(" dev: TIME=\"%ld.%ld\"\n", (long)dev->bid_time, (long)dev->bid_utime);
477 printf(" dev: PRI=\"%d\"\n", dev->bid_pri);
478 printf(" dev: flags = 0x%08X\n", dev->bid_flags);
479
480 list_for_each(p, &dev->bid_tags) {
481 blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags);
482 if (tag)
483 printf(" tag: %s=\"%s\"\n", tag->bit_name,
484 tag->bit_val);
485 else
486 printf(" tag: NULL\n");
487 }
488 printf("\n");
489}
490
491int main(int argc, char**argv)
492{
493 blkid_cache cache = NULL;
494 int ret;
495
bigbiff7b4c7a62015-01-01 19:44:14 -0500496 blkid_init_debug(BLKID_DEBUG_ALL);
bigbiff bigbiffe60683a2013-02-22 20:55:50 -0500497 if (argc > 2) {
498 fprintf(stderr, "Usage: %s [filename]\n"
499 "Test parsing of the cache (filename)\n", argv[0]);
500 exit(1);
501 }
502 if ((ret = blkid_get_cache(&cache, argv[1])) < 0)
503 fprintf(stderr, "error %d reading cache file %s\n", ret,
504 argv[1] ? argv[1] : blkid_get_cache_filename(NULL));
505
506 blkid_put_cache(cache);
507
508 return ret;
509}
510#endif